The present invention relates to a heat-exchange coil assembly, and more particularly to a heat-exchange coil assembly accommodated in a drum for exchanging heat between a heat-exchange medium flowing in the drum and a heat-exchange medium flowing in the coil.
The inventor for the present invention has already proposed, as disclosed in Japanese Patent Laid-Open Publication No. 8-54192, a heat-exchange coil assembly in which a plurality of heat-exchange coils each having a different winding diameter are arranged so that they have a common center line. With this heat-exchange coil assembly, there are provided the advantages that the heat exchange efficiency can be improved without making larger a drum capacity of the heat exchanger, and that the heat exchange capability can freely be set.
In this type of heat-exchange coil assembly as shown in FIG. 1, the ends 6-1, 2, 3, 4, and 5 of the heat-exchange coils are linked to an inlet header 2 and the ends 7-1, 2, 3, 4, and 5 to an outlet header 4 at their center lines B--B and B'--B', respectively. As shown in FIG. 27, the linkage is achieved by welding the heat-exchange coils 28-1, 2, 3, 4, and 5 to the same side of the inlet header and outlet header. Because of this configuration, a pitch P' between any adjoining two of the heat-exchange coils 28-1, 2, 3, 4, and 5 must be set to at least a value obtained by adding a width equal to 2a, where a equals the width of the weld to the external diameter d of the heat-exchange coil tubes, as shown on FIG. 3. This required configuration disadvantageously makes it difficult to realize a small-sized and compact heat-exchange coil assembly.